Cutter



Sept. 30, 1941.' v. H. BAKER 2,257,448

CUTTER Filed June 19, 1939 INVENTOR 97,11 A ML Patented Sept. 30, 1941 CUTTER Virgil H. Baker, Springfield, Ohio, assignonto Elliott Company, Pittsburgh, Pa., a corporation of Pennsylvania Application June 19, 1939, Serial No. 279,832

Claims.

This invention pertains to new and improved cutters. and more particularly, to improved cutters for tube cleaning such as are employed in removing scale, carbon, etc, from interiors of boiler or oil refinery tubes.

In removing deposits from the inside of tubes or pipes, relatively high speed rotating cutter heads equippedwith cutter wheels are employed. Since the teeth of the cutter wheels are milled to a sharp edge and are thrown at ahigh speed against the walls of a tube by centrifugal force, a grinding action is created which removes a deposit from the tube.- It will be apparent that internal abrasion is unavoidable and thus must be kept at a minimum at all times. Such abrasion isparticularly serious in oil refinery applications where alloy tubes are used and are quite expensive from the standpoint of original cost, maintenance, and replacement. It is customary to caliper the tubes in oil refinery applications on the inside after each cleanout; the tubes are generally of extended length and are fully calipered along such length in order to determine the wall thickness. The tubes are removed when the thickness reaches a minimum for the'pressure under which they operate. It is difiicult t accurately caliper the inside of a tube having an irregular surface, with the result that the operator may be misled as to the actual thickness; rupture causes serious damage.

Rough and deep indentations on the inside of tubes are also undesirable due to the more rapid accumulation of deposit and the difliculty of thereafter cleaning the tube. Small particles gather in such irregularities and continue t build up until the flow is obstructed.

.Heretofore, considerable "difficulty has been encountered in devising a suitable type of cutter for eliminating the so-called gear ortrack effect.

Inview of the above considerations, it has been an object of my invention to provide a new and improved form of cutter that effects a substan tially. smoothtrack on the surface being cleaned.

Another object of my invention has been to provide an inexpensive and practical form of cuttor for the purposes enumerated. g

A further object has been to determine the factors that govern the type of grinding action effected upon the surface being cleaned.

These and many other objects of my invention will appear to those skilled in the art in View of the description, the drawing, and the appended claims.

Figure 1 is a side elevation of a tube cleaner having cutters embodying my invention;

by an ordinary type of cutter; and

Figure 7 is an enlarged perspective section similar to Figure 6, but showing an improved effect that may be accomplished by a cutter embodying the features of my invention.

As will be appreciated from a study of Figure 6, the progressive action of the teeth of an ordinary type of cutterwill cut complementary gearlike indentations thatcorrespond to the cutting face of the cutters being employed. I have discovered that a cutter having cutting teeth of equal space will strike the tube at approximately the same place with each rotation and that this results inthe track or groove cutting before mentioned. I have been able to eliminate this effect,

to minimize the cutting action, and to provide a relatively smooth cut surface by employing a' series of substantially uniformly spaced teeth with one exception. In other words, I provide an. additional spacing between one pair of adjacent teeth that is not uniform as compared with the spacing of the others. In this connection, I have found that the desired effect is also insured by employing an uneven or an odd number of teeth.

I have also determined that in addition to:

employing an odd number of teeth, it is preferable to provide an odd fractional spacing b-ctween a pair of teeth to obtain the most effective results. In this connection, I have found an odd fraction of a third to be very satisfactory.

In Figure 1, ill shows a suit-able type of cleaning head providing with frustro-conical cutters l l and cylindrical cutters l2 constructed and arranged in accordance with the principles of my invention. Figures 2 and 3 show the cylindrical form of cutters l2 while Figure 4 shows a frustroconical type I as shown, both types are provided with additional spacing l3 and an odd number of teeth.

In making a no-track cutter, I preferably di vide the periphery of the cutter head into an evenly distributed number of spaces. And, on the final cut, the divided head isso arranged that it advances the work in such a manner that the groove as now out by the milling cutters is advanced by a space that is larger by a fraction, preferably by a third, than the preceding spaces measured on any symmetrical arc.

As will be appreciated from a comparison of Figures 6 and 7 of the drawing, a cutter constructed in accordance with my invention is also much more efiicient, particularly in cleaning out hard, brittle, or coke-like substances; as random chisel-like blows are very effectively delivered and less power is required. On the other hand, an ordinary type of cutter provides less freedom for removal of the chips, and its impact is delivered tionally preferably having at least one tooth or an odd number of teeth of non-uniform dimension in this respect. As shown in Figure '3, the dimension a is non-uniform or greater than the dimension D of the uniform-dimension series of teeth. This is true regardless of whether a wider spacing I3 is provided or Whether the tooth is 7 provided with a greater width, see the line of Figure 5.

In carrying out the invention, I hav found that th number of odd spaces is relatively unimportant provided the' aggregate increase of each space equals substantially one-third of the uniform space. One space, for example, can be formed substantially one-third less in width than the other uniform spaces to obtain th trackless results. Y

It is believed one ofthe important features of the present invention rests in the provision of a cutter element having a series of substantially uniformly spaced cutting, teeth about the periphery thereof with a spacing between at least one pair of teeth being non-uniform and having a.

width differing from the uniform spacing by an odd fractional amount taken, for example, from the series beginning one-third, one-sixth, etc. Also in accordance with my invention, it is im portant that the total width of non-uniform spacing should be such that the aggregate must vention, I have shown certain formsthereof, it

will be, appajrent'to those skilled in the art that other suitable forms may be employed and that suitable modifications, substitutions, additions, etc., may be exercised-without departing from the spirit and scope of the invention as indicated by the appended claims;

I claim: I

1. In a tube cleaner, a cutter element operably associated therewith, said cutter element having a series of substantially-uniformly spaced cutting teeth about the periphery thereof, the spacing between a pair of teeth being non-uniform and having a different width than said above-mentioned uniform spacing.

2. In a tube cleaner, a cutter element operably associated therewith, said cutter element having a series of substantially-uniformly spaced cutting teeth about the periphery thereof and having a tooth non-uniformly spaced with respect to another tooth and having a greater width of spacing that said above-mentioned uniform spacing.

3. In a tube cleaner, a cutter element operably associated therewith, said cutter element having a series of cutting teeth of substantiallyuniform-peripheral dimension comprising teeth width and spacing and having a tooth of nonuniform peripheral dimension comprising tooth width and spacing.

' 4. In an article of manufacture for trackless tube cleaning, a cutter element having a plurality of teeth about its periphery, said cutter element having a tooth whose spacing with respect to an adjacent tooth is different than the spacing between other teeth, such other teeth having a substantially uniform spacing with respect to each other, and being of substantially the same radial length.

5. In an article of manufacture for trackless tube cleaning, a cutter element having a plurality of cutting teeth about the periphery thereof, said cutting teeth being an odd number, at least a portion of said teeth having a substantially uniform spacing therebetween, the spacing between a, minority of said teeth being different than the spacing between other teeth, all of said teeth being of substantially the same radial length.

6. In a tube cleaner, a cutter element operably associated therewith, said cutter element having a series of substantially-uniformly spaced cutting teeth about the periphery thereof, the spacing between at least one pair of teeth being nonuniform and' having a width differing from said above-mentioned uniform spacing by an amount substantially equal to one-third of the uniform spacing, divided by an integer.

7. In a tube cleaner, a cutter element operably associated therewith, said cutter element having a series of substantially uniformly spaced cuttingteeth about the periphery thereof, the spacing between at least one pair of teeth being non-uniform and having a width differing from said above-mentioned uniform spacing by a fractional amount of substantially one-third.

' 8'. In a tube cleaner, a cutter element operably associated therewith-said cutter element having cutting teeth, a majority of said cutting teeth being'of substantially. uniform peripheral dimension comprising teeth width and spacing, and a minority of "said teeth being of substantially nonuniform peripheral dimension comprising teeth width and spacing.

9. In an article of manufacture for tube cleaning, a cutter element having a series of substantially uniformly spaced cutting teeth about the periphery thereof, said cutter element also havthe total non-uniform spacing having a different width than the uniform spacing.

10. In an article of manufacture for tube cleaning, a cutter element having a series of substantially uniformly spaced cutting teeth about the periphery thereof, said cutter element also having at least a pair of cutting teeth about the periphery thereof having a substantially nonuniform spacing therebetween, the total non-uniform spacing having a different width 

